bass in its 95% list (CPUE^ was 0.51 , 1.9% of the total). 

 Fish Health Determined by External Visual Inspection . 



Sediment-contact (benthic) fishes (e.g., common carp) had higher incidences of 

 externally-visible abnormalities (eg , sores, eroded fins) than water-column fishes 

 (eg., bluegill) (Figure 2). A total of 108 fishes collected in 1996 had abnormalities, of 

 which 77 (71.3%)) were sediment-contact fishes. There was a longitudinal 

 (upstream-downstream) gradient in the percentage of fishes with abnormalities, with 

 highest incidence in the upper waterway, particularly in Dresden Reach. Of the 76 

 benthic fishes collected in the upper wateiway, 26 of them (34.2%) had external 

 abnormalities. In tne middle and lower wateoA'ay, only 5.9%o and 3.0% of benthic 

 fishes showed abnormalities, respectively. This trend was documented during 

 previous years also (Lerczak et al. 1994:68, 1995:39, 1996:29). Incidence of water- 

 column fishes with abnormalities was only slightly higher (2.7%) in the upper 

 v/aterv/ay than in the middle (0.3%) and lower (1.1%) waterway. _^_i;'w3 __ '"^f^ 



CONCLUSIONS ^;.^^.f rr _^f ^ ., ^^ 



>-'y^ U.L- ^'~ ^7% '■'^•'^ 



Samples collected by electrofishing on the Illinois River Waten<vay during 



August and September 1995 provided evidence that fish communities in the lower, 



middle, and upper waterway are substantially different in terms of species 



composition by number and by weight. Of 76 species and 3 hybrids collected 



previously during segments of project F-101-R, 41 species and 2 hybrids were 



collected in 1996. Th,e mud darter has not previously been collected during Long- 

 C^ ^^'^-^<- Gaa^'A ^CuJV:^ ^^'^'^- 



r^ijudMjL 25 



